1. Field
The present invention relates to a composition for a gasket and a gasket produced from the composition. More specifically, the present invention relates to a composition for a gasket capable of preventing leakage of water toward a door upon a washing operation of a drum washing machine, and absorbing vibration of a tub transferred to a cabinet, thus reducing overall vibration of the washing machine, and exhibiting superior heat resistance (high-temperature tensile strength and the capability to restore an original state after exposure to high temperatures), and a gasket produced from the composition.
2. Description of the Related Art
Ethylene propylene rubbers, also called “ethylene propylene diene monomers (EPDMs)” are generally used for door gaskets of drum washing machines. However, in order to satisfy physical properties such as tensile strength, heat resistance, high-temperature restoring force (defined as the capability to restore initial dimensions after exposure to high temperatures) and chemical resistance of ethylene propylene rubbers, the process of molding ethylene propylene rubbers necessarily requires a chemical reaction, so-called “cross-linking”. Such a cross-linking reaction allows rubbers to have a three-dimensional network structure required to impart elasticity to the rubbers. Accordingly, although time may vary depending on the size and shape of gasket components, it commonly takes 5 to 10 minutes to complete a series of processes including melting, injecting, cross-linking and releasing, after master batches are supplied, thus disadvantageously lengthening an overall molding time and causing low production efficiency. Furthermore, ethylene propylene rubbers are thermosetting rubbers cross-linked by addition of cross-linking agents, thus disadvantageously making it extremely difficult to recycle defective products obtained in the production process.
Japanese Patent No. 3,373,833 discloses a thermoplastic elastomer composition including a hydrogenated block copolymer, a softener for non-aromatic-based system rubbers and a modified polyolefin-based resin, where the composition exhibits superior adhesion force to low-hardness metal components and can be simply supported and integrated with the metal components by injection-molding the composition on the surface thereof.
Conventional drum washing machines having a boiling function that necessarily requires the capability to restore their original state immediately after they are deformed at high temperatures. However, the high-hardness thermoplastic elastomer disclosed in the afore-mentioned Japanese patent has a disadvantage of insufficient heat resistance.